Wednesday, March 05, 2008

from AndyS

Profilin'

A few months ago I was exchanging emails with James Hoffmann and I offered to build him a profiling pump for his espresso machine. A profiling pump is one that can be programmed to accurately deliver pressures that follow a predetermined curve. Conventional pumps don't allow this, they merely can be set for one fixed pressure.

Well, I still haven't delivered on my offer, but I will. The other day in New York we met up in person and talked a bit about the project. James said something like, "pressure profiling is the last frontier in espresso, everything else has been taken care of." But I had to differ.

As I've said (too many) times before, temperature profiling has remained mostly unexplored territory by the current crop of new wave baristas. As soon as I get James's pump built and shipped, I need to design and fabricate my homemade espresso machine that will allow experimentation with flat temperature profiles, declining temperature profiles, etc. Why should Sean L and John E have all the fun?

And Nick, when you asked me many months ago why I didn't ditch the Silvia and get some kind of commercial espresso machine, this is mainly the reason. All the commercial machines are compromised and designed to a price point. That's not to say that they aren't great pieces of equipment. But they are limited in what they can do.

For me, the fun is in the amateur engineering and in discovery. When the machine can accurately profile both temperature and pressure, maybe then we'll be a the last frontier. Maybe....

7 Comments:

I don't think I said everything else was sorted, and if I did then I didn't mean to (the jetlag! the jetlag!)

I do think pressure profiling is an area that is relatively unexplored compared to many other aspects of preparation and I think there is a good chance the cup could be improved through a better understanding and control of it.

I can't wait to start playing and being reminded of how little control we have, how inconsistent I am and how much I love coffee!

About eighteen month ago at Jay's Shave Ice, we ended up doing some de facto experimentation with declining pressures on a La Marzocco Linea 2AV. Surprisingly, the results were very positive.

Unfortunately, I didn't take any notes and don't remember specifics but it has been in the back of my mind as something to revisit and pay attention to.

The parameters of our experience were to brew at 8.5 BAR for roughly the first fifteen seconds of the shot then at line pressure (6BAR) for the remainder of the shot.

To be quite honest, this happened not because of an intention to learn about declining pressure profiles but rather because of a faulty thermal switch on the pump motor that would "overheat" and shut off about 15 seconds into the shot.

Hi James: I didn't mean to overanalyze what you said. No worries: all the espresso parameters remain fair game for exploration.Hi Jay: It's amazing how many discoveries are unintentional; "accidents" are at the core of many of them. Kudos to you for noticing that the result of your pump problem may be something good.